An adaptive de-interlacer can convert an interlaced video signal into a progressive video signal, and comprises a motion detector, an intra-field interpolator, an inter-field interpolator, a motion aliasing artifact detector and a blending unit. The motion detector generates an alpha value for each interpolated pixel in a current field of the interlaced video signal based on successive fields of the interlaced video signal. The intra-field interpolator outputs an intra-field interpolated pixel based on the current field, and the inter-field interpolator also outputs an inter-field interpolated pixel based on the successive fields. Afterward, the motion aliasing artifact detector detects whether the interpolated pixel is located in a motion aliasing area. The blending unit receives and mixes the intra-field interpolated pixel and inter-field interpolated pixel based on the alpha value from the motion detector and the detection result from the motion aliasing artifact detector so as to determine the interpolated pixel.